Hexenyl-l,3,2-benzodioxaborole

The submitters report bp 86-87°C (0.3 urn). (E)-1-Hexenyl-1,3,2-benzodioxaborole is quite air stable, but it can slowly hydrolyze to boronlc acid and turn brown on repeated use in air. The submitters recommend storing it at refrigerator temperature In a bottle purged with nitrogen and capped with a rubber septum. Alternatively, the crude 1-hexenyl-1,3,2-benzodioxaborole can be used for the next coupling reaction without purification. In this case, the unreacted 1-hexyne should be removed under reduced pressure (0.1 mn for 30 min), because it also reacts with (Z)-6-bromostryrene to afford (lZ)-l-phenyl-l-octen-3-yne. In this manner the expected diene was obtained in a yield of 86%. 

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